Integrated mathematics and science teaching and learning is a widely advocated yet largely unexplored phenomenon. This study involves an examination of middle school integrated mathematics and science education from two perspectives: in theory and in practice. The theoretical component of this research addresses the ill-defined nature of the phrase "integrated mathematics and science education", and presents a conceptual framework in the form of a Math/Science Continuum to lend clarity and precision to this phrase. The theoretical framework was used to guide the design and implementation of the second component of this research, a qualitative investigation of two case studies of middle school integrated mathematics and science education. Following an outline of the design of this study, results from the two case studies are presented. This paper concludes with a discussion of three implications of this study for teaching and teacher education. Contains 18 references. (Author)